Ostriker 9318185 The Grand Challenge Application Groups competition provides one mechanism for the support of multidisciplinary teams of scientists and engineers to meet the goals of the High Performance Computing and Communications (HPCC) Initiative in Fiscal Year 1993. The ideal proposal provided not only the opportunity to achieve significant progress on (1) a fundamental problem in science or engineering whose solution could be advanced by applying high performance computing techniques and resources, or (2) enabling technologies which facilitate those advances, but also significant interactions between scientific and computational activities, usually involving mathematical, computer or computational scientist, that would have impact in high performance computational activities beyond the specific scientific or engineering problem area(s) or discipline being studied. This project brings together a balanced, critical mass team of astrophysicists, computational scientists and computer scientists, as well as the technical resources of two NSF supercomputing centers, to mount a focused attack on what is presently one of the most exciting and fundamental problems in the physical sciences: "What is the origin of large-scale structure in the universe and how do galaxies form?" There is abundant observational data sufficient knowledge of the physical laws and mathematical techniques required to understand the origin and evolution of cosmic structure. Yet, it is difficult to confront theory with observation in detail owing to the inherent complexity of these systems and the difficulty of simulating multiple length-scale interactions. However, recent developments in multiscale numerical algorithms by members of our Grand Challenge Application Group (GCAG) and their efficient implementation on scaleable parallel supercomputers should enable the investigators to overcome these limitations. The GCAG will explore the use of: (i) different numerical algorithms (grid-based, particle-based, and hybrid ( grid+particle) to solve the physical equations governing gas, radiation, dark matter and gravity in an expanding universe; (ii) different adaptation strategies (adaptive mesh refinement, hierarchical tree) to achieve efficient, multiscale solvers capable of resolving length scales of interest over 4-6 orders of magnitude; (iii) different programming models (data parallel, SPMD, object parallel) to express these complex, adaptive algorithms in an efficient and portable way on different parallel architectures (TMC's CM5, Intel PARAGON, Cray T3D, Convex MPP) available to the investigators; and (iv) new software technology (e.g. pC++) to develop compilers, optimization designs and performance analysis tools which allow the most efficient implementation of the above strategies in order to expose the various computational and computer science issues required to construct a portable, scaleable application for teraflop systems expected later in this decade. This unique numerical laboratory-will allow the investigators to compare theories of the origin of large-scale structure with the observed universe, to discard incorrect models and hopefully to determine the elements of a viable theory. This HPCC Grand Challenge will be extremely data and UO intensive, pushing current hardware and software systems and solutions to and beyond their limits. The investigators will work with staffs of the Pittsburgh and Illinois supercomputer centers as well as the computer vendors to develop practical and efficient strategies for the storage, visualization and analysis of massive numerical data sets of use to this and other HPCC applications. This award is being supported by the Advanced Projects Research Agency as well as NSF programs in astronomy and computer sciences.
